Integrated optoelectronic technology allows computing devices to send and receive data at unprecedented speeds. A typical integrated optoelectronic system could include lasers, modulators, multiplexers/demultiplexers, photo-detectors, and other passive components such as filters, couplers and waveguides.
Silicon photonics use silicon as an optical medium. The silicon is patterned with sub-micrometre precision, into microphotonic components used in fiber optic telecommunication systems. Silicon photonic devices can be made using existing semiconductor fabrication techniques, and because silicon is already used as the substrate for most integrated circuits, it is possible to create hybrid devices in which the optical and electronic components are integrated onto a single microchip.
In some implementations, silicon photonics rely on SOI wafers to create passive optical waveguides. While SOI based waveguides provide a strong confinement of optical field and the ease of integration with other optical/electrical components, it is not without tradeoffs. For example, the cost of SOI processes is substantially higher than Si processes, including both substrate and fabrication expenses. Also, the buried oxide in SOI tends to block excess heat that is inevitably generated by the optical/electrical components, and therefore may feature poor thermal conductivity and stability. For these reasons, many foundries still implement optical waveguide devices in bulk Si. However, it has been found that long Si waveguides can swing out of position, thus affecting the efficiency of waveguide transmission.